A_xB_(1-x)C_yD_(1-y)型四元混晶光学声子性质的研究

Investigation of optical phonon properties in A_xB_(1-x)C_yD_(1-y) mixed crystals

针对现有理论的不足,提出了新的A_xB_(1-x)C_yD_(1-y)型四元混晶中晶格振动理论模型,利用ClausiusMossotti公式对运动方程组加以简化,同时引入波恩-黄昆方程消除微观变量,最终得到混晶声子频率对组分(x,y)的依赖关系。该理论模型优点在于只需知道AC、AD、BC和BD四种二元混晶的若干参数(光学声子横模频率、纵模频率和晶体的静态介电常数和光学介电常数),就可求出A_xB_(1-x)C_yD_(1-y)型四元半导体混晶的光学声子特性,当组分取边界值时,结果则对应三元和二元晶体。理论结果与实验数据符合较好,对今后实验有一定指导作用.

In order to overcome the shortcoming involved with the current theory, the new theory model of lattice vibration in AxB1-xCyD1-y quarternary mixed crystals was described. Using the Clausius-Mossotti formula for simplifying the motion equations, and Born-Huang equations for eliminating microscopic variables, the relationship between optical phonon and elemental concentrations （x, y） of mixed crystals was obtained. The advantage of the proposed theory model is that the optical phonon character of AxB1-xCyD1-y quarternary mixed crystals can be solved only by several parameters of the binary mixed crystals such as AC, AD, BC and BD. The parameters include TO mode frequency, LO mode frequency, static dielectric con- stant and optical dielectric constant. Taking the boundary values, the results are corresponding to ternary mixed crystals and binary mixed crystals. The theoretical results and experimental data meet well with each other, which give certain guidance to future experiments.